Parallel ruling means



NOV. l5, 1949 Q E FRQEUCH 2,488,284

PARALLEL RULING MEANS Filed Sept. 20, 1946 2 Shee'ts-Sheet l Nov. 15, 1949 G. E. FRoELlcl-l 2,488,284

PARALLEL RULING MEANS Filed sept. 2o, 194e 2 sheets-sheet 2 6g Tg 2i n 33 2.9 V3 @j ,f5 27 f Patented Nov. 15, 1949 PARALLEL RULING MEANS George E. Froelich, Two Rivers, Wis.,- assignor to Hamilton Manufacturing Company, a corporation of Wisconsin Application September ,20, 1946, Serial No. 698,180

(Cl. '3S-80) Claims.

This invention relates to parallel ruling means for mechanical drawing tables which commonly include a large size drawing board with a straight edge device spanning the board and a cable engaging the board and straight edge device for guiding the straight edge device in its movements on the board.

Among other objects, the present invention aims to provide an improved means of this character of enhanced simplicity of operation and economy of manufacture while insuring markedly easy, quiet and consistently true operation at all times.

In an important aspect, the invention contemplates a combined straight edge device and parallel rule attachment which can be applied to any drawing board by the user thereof with a minimum of effort, one purchase by the user covering everything that is necessary to the installation.

These and other objects and advantages will be apparent from the following detailed description, taken together with the accompanying drawings, of an illustrative embodiment of the invention, and in which drawings- Figure 1 is a plan view of parallel ruling means embodying the present invention, parts being broken away intermedially to save space;

Figure 2 is an enlarged cross-sectional view taken on the line 2-2 of Figure 1, looking in the direction of the arrows, and similarly broken away;

Figure 3 is a section taken on the line 3-3 of Figure 2; and

Figure 4 is an elevational view of, one of the rear corners of the board showing the wire attachment and being a view on the line 4-4 of Figure 1.

Referring in detail to the illustrative construction shown in the drawings, the reference numeral I'l indicates a drawing board of the usual wood construction and which may be in relatively large sizes. Along its side edges the drawing board Il desirably has steel cleat pieces I2 and I3, these being in this instance in the form of a box-like member, having its upper face I4 del pressed into the board at each side so as to be flush with the working surface I5 of the board, a kerf I6 in the board receiving the down-turned flange II of the cleat. At its lower face I8, each cleat is extended downwardly below the board to enhance its height and is then bent up to engage the board as at I9 where a screw 20 passing through a slot 2| xes the engagement. This slot may be elongated in the direction of the cleat member so as to permit adjustments of the cleat with respect to the board.

For parallel ruling purposes, the board II has associated therewith a straight edge device indicated generally by the numeral 22, which is attached to the board to slide over the. drawing surface I5 from front to rear of the board by translatory movements in which the straight. edge device is maintained inv parallel relation with the board so that lines drawn by aid of rthe straight edge 2-3 of the edge strip 24 of the straight edge device will be parallel to each other in all posif.- tions of the straight edge device.

In accordance with the present invention, the straight edgev device 22 comprisesl a blade body 25, preferably of aluminum for lightness, strength and ease of adjustability, this body being of su'lcient lengthV to span the boardv from side to side thereof. Adjacent its longitudinal center line the blade body is upwardly channeled asy at 26 to provide an inverted housing for av roller shaft 21 which extends from end to end of the blade body and is journaled at each end thereof in a bearing block 28 whichV is' secured within the channeled housing 26 as by screws 29. The bearing blocks advantageously incorporate a, metal impregnated with oil, such as is available on the market.

To the ends of the roller shaft 21 which project beyond the bearing blocks 28 are suitably secured, as by press-fity or welding,a relatively large roller or wheel 30 at the left-hand end of the blade body 25 and 3I at the. right-hand end. Semi-circular cover or guard platesA 32 and 33 respectively are` securedv over the rollers (III and 3 I, as by screws 3II` which pass through, anges- 315 extending laterally from each guard plate, the screws passing` intothe flat margins 36 and4 31 of the blade body 25.

The guide rollers 30 and 3l are desirably grooved advantageously each in a spiral asy at. 38 which is here shown in the form of an external screw thread on the peripheral edge of the roller, this threadv in the present instance being what might betermedr a right-'hand screw thread in the sense that when one looksV atV either roller atan end thereof the threadsv rotating. toV the` right proceed away from the eye of: the beholder, for the purpose next described.

Further in accordance with thepresent-inveri tion, a flexible member comprising cable sections 39 and 4,0, here shownA as Sections ofA wire, such. as piano wire, are looped about theguidev rollers 30 and 3| and anchoredtothe drawing board II on opposite sides of the straightl edgeA device, that is, adjacent the front and reared-gesof the draw-L ing board. to provide guide wires or guide cords for the straight edge device. Each wire is passed first under, then up and over the roller and down again as at 40a, the. wire loop 40a lying in. or trained inthe groove 38` of the rollerl threadsin each case, and thus meshing-therewith, following the spiral. The angle for each flexible member is coordinated with or substantially equal to the lead angle of thev groove' cffits` roller respectively, so as not to buckle or distort the wire.

Adjacent the front edge 4| of the drawing board the wire 39 is anchored thereto as by a screw 42 passinginto the side of the board through the steel cleat'fl2. This screw 42 is elongated and carries a spacer sleeve 43 which receives between the outer end thereof and the head of the screwf f edge device close to the drawing board surface I5 at all times, and particularly if the drawing board be mounted as it may be upon a stand by which angular movements from horizontal to vertical of the drawing board are permitted, a pair of depending arms 55 are provided at each end of the straight edge device which slidingly embrace, as

where it is anchored as at 48 to one end of an exf pansion coil spring 49, the other end of which is Yanchored as at. 50 to a projection 5I extending rearwardly of the anchor 4plate 41, the latter being secured as by'screws 52 to the rear edge 46 of the board. Y

VAt the other side of the board, the wire 40 is screwed as at 53 tightly to the board adjacent the front edge 4| thereof, and then, after being looped aboutIthe`roller-3I, inclines laterally outwardly from the cleat i3 toward the rear edge 46 of the board where it is anchored to another one of the anchor plates 41. At this side of the board, however, the anchor plate 41 has its screws 52 located vcloser tothe board edge and so much so that the anchor plate is offset at its outer end as at 54, laterally of vthe board at this side, to accommodate and maintain the lateral inclination of the Wire 40 already referred to, the wire 4i) being anchored to its anchorfplate 41 in a manner similar to the wire 39 in other respects and which need not berepeated. f. .,Thus, .in this instance both Wires 39 and 40 incline laterally in the same direction and dene inclined sides of a parallelogram, the other two sides of which are the front edge 4| and rear edge 46 of the board, and both wires are resiliently connected as by theanchor coil springs 49 to the rear edge Aof the board so as to maintain vthe wires taut when the straight edge device 22 moves relatively to. the wires which nevertheless remain looped about the rollers 39 and 3| respectively, in all movements of. the straight edge device.

Since the'wir'es aremaintainecl taut they are held in parallel to each other and the inclination of the wires accommodates the travel thereof, and particularly the loop 40a thereof, in the spiral grooves 38 ofthe rollers. In other words, when the straight edge device is near the front edge 4| of the drawing board, the loop 40a of the Wire 39 is at the left-hand end of the roller 39, that is, the end of the spiral groove 38 farthest away from the drawing board side. At the same time, the loop 40a of the wire 40 is at the left-hand end, which in this instance, is the end nearest the drawing board, of the spiral groove 38 of the roller 3 I. As now the straight edge device moves toward the rear of the board, the loops 49a, of the wires 39 and 49 travel to the right relatively on their respective rollers so that when the straight edge device is near the rear edge 46 of the board the wire loop 40a of the wire 39 is at the end of the roller 30 nearest the drawing board while the loop 49a of the wire 46 is at the end of the roller 3| farthest from the drawingboard.

Since the rollers 30 and 3| are keyed to the shaft 21 to rotate simultaneously therewith and r are of equaldiameter the straight edgedevice is maintained at all times parallel to the edges 4| and 46 `of .the drawing board, once, it has been initially so adjusted and the wires anchored in place.

tion.

by inturned portions 56 of the arms, the steel cleats I2 and I3 respectively at each side of the drawing board. Each arm 55 may be secured as by a screw 51 to one of the semi-circular guard plates 32 and 33 respectively and to hang there- 'from Aas described. The relatively great vertical length of these arms 55, accommodated by the downwardly offset Walls I8 of the cleats I2 and I3, insures against undue rocking movements of the blade body 25.

u The blade body 25 is desirably oiset downwardly as at 58 along its margin 31 so as to compensate for the thickness along its other margin 36 ofthe usual transparent strip 24 which may be suitably securedr thereto as at 59, by cement or the like. If desired the margin 31 may have felt pads 66 thereunder.

It may at times be desiredto impose a drag upon the movements of the straight edge device or inhibit such movement entirely, for example when the board is disposed at a great angle approaching the vertical, and, for this purpose, a frictional drag is here provided in the form of a collar block 6| disposed within the channeled housing 26 of the blade body 25 encircling the shaft- 21 and provided with an upstanding screwthreaded stud portion 62 which passes outwardly through a hole 63 in the housing 26 and has screwed thereonto a knurled thumb nut 64, which when screwed down pulls the collar block 6I upso as to jam the shaft and prevent or restrain turning of the latter.

Since normal working positions of the drawing board, for convenience of the draftsman, dictate an elevation of the rear edge 46 above the front edge 4I, the upper edge 65 of the inverted channeledy housing 26 providesa convenient ledge for the draftsmans pencils, triangles, etc. Y The anchor vplates 41 are desirably rounded as at 66 where the wires pass thereabout, to avoid a sharp edge which might out the wire andalso to permit the springs 49 to exert a tautening inuenceupon the wires inspite of the bend therein adjacent the spring. Furthermore, the relatively large diameter of the rollers 30 and 3| avoid a sharp bend in the wire so that a wire of the tensile strength and hardness of a piano Wire may be used4 withoutY kinking, and this further insures smooth and quiet movements of the straight'edge device while maintaining Vsaid movements incon- Ysistently true'parallelism at all times. The wires and anchoring means for the wires may be sold with the blade as a unit. Y If the drawing board should swell or shrink because of atmospheric conditions, the springs 49 will compensate for such changes in dimensions of the drawing board and maintain the wires .39 and 40 taut and parallel. No moving cords are required and no oiling is necessary. The device can be readily applied to any drawing board and even one without the steel cleats I2 and I3, although the latter are preferred for ease of opera- The .blade being. of aluminum .may be readily bent back into original shape if it becomes bowed after a period of use, or may be bent to stay in anyl desired position to make the edge straight. If it be desired to adjust the device, one of the wires may be loosened, the blade fixed in parallel by the aid of an ordinary T-square and the Wire re-tightened.

The wires will not stretch as do fiber or textile cords and will wear indefinitely. The threaded roller causes the loop 40a of the Wire to assume a somewhat helical form at all times, as shown in the drawings which guards against the wire interfering with itself and insures free running.

The invention is not intended to be limited to details of construction shown for purposes of illustration, and such changes may be made as fall within the scope of the appended claims without departing from the invention.

The invention having been described, what is here claimed is:

1. Parallel ruling means comprising a drawing board, a straight edge device spanning the board, a roller carried at each end of the straight edge device, a spiral groove on each roller, a flexible member intermediately looped about each roller and trained in the grooves respectively, and an anchorage on the board for the flexible members on opposite sides of the straight edge device, whereby the straight edge device is movable relatively to the flexible members but confined to translatory movements with respect to the board, an anchorage for each flexible member being at a different distance from the board at one edge of the board than at the other edge to place the flexible members at an angle to the side edges of the board to accommodate lateral displacement of the flexible members with respect to the spiral grooves, said angle for each flexible member being substantially equal to the lead angle of the groove of its said roller respectively.

2. Parallel ruling means comprising a drawing board, a straight edge device having a shaft running longitudinally thereof, a roller carried at each end of the shaft and keyed to rotate therewith, a spiral groove on each roller, a flexible member intermediately looped about each roller and trained in the grooves respectively, and an anchorage on the board for the flexible members on opposite sides of the straight edge device, whereby the straight edge device is movable relatively to the flexible members but confined to translatory movements with respect to the board, an anchorage for each flexible member being at a different distance from the board at one edge of the board than at the other edge to place the flexible members at an angle to the side edges of the board to accommodate lateral displacement of the flexible members with respect to the spiral groove, said angle for each flexible member being substantially equal to the lead angle of the groove of its said roller respectively.

3. Parallel ruling means comprising a drawing board, a straight edge device having a shaft running longitudinally therethrough, a roller carried at each end of the shaft and keyed to rotate therewith, a spiral groove on each roller, a flexible member intermediately looped about each roller and trained in the grooves respectively, and an anchorage on the board for the flexible members on opposite sides of the straight edge device, whereby the straight edge device is movable relatively to the flexible members but confined to translatory movements with respect to the board, an anchorage for each flexible member being at a different distance from the board at one edge of the board than at the other edge to place the flexible members at an angle to the side edges of the board to accommodate lateral displacement of the flexible members with respect to the spiral grooves, said angle for each flexible member being coordinated with the lead angle of the groove of its said roller respectively, the fiexible members being of wire and the rollers being of relatively large diameter with respect to the shaft so as not to unduly bend the Wire.

4. Parallel ruling means comprising a straight edge device having a shaft running longitudinally therethrough, a roller carried at each end of the shaft and keyed to rotate therewith, a spiral groove on each roller, a exible wire member intermediately looped about each roller and trained in the grooves respectively, and an anchorage for the flexible members on opposite sides of the straight edge device, whereby the straight edge device is movable relatively to the flexible members but confined to translatory movements thereof, said anchorage including a tension coil spring attached to each wire an anchorage for each flexible member holding the exible members at an angle to accommodate lateral displacement of the flexible members with respect to the spiral grooves, said angle for each wire being Acoordinated with the lead angle of the groove of its roller respectively.

5. In parallel ruling means, in combination, a straight edge device, a shaft rotatably carried longitudinally thereof, a roller at each end of the shaft rigid with said shaft, said rollers being spirally grooved by threads pitched in the same direction, a exible member intermediately looped about each roller and trained in the grooves respectively, and anchorages for each flexible member on opposite sides of the straight edge device, a line joining the anchorages for the flexible member for each roller being at an angle to the straight edge device other than a right angle and said lines being parallel, to accommodate shifting movements of the flexible members relatively axially of the rollers in translatory movements of the straight edge device, said angle corresponding to the lead angle of the grooves of the rollers.

GEORGE E. FROELICH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 550,413 Laughlin et al Nov. 26, 1895 714,594 Marx Nov. 25, 1902 1,682,083 Johnston Aug. 28, 1928 1,977,213 Slobey Oct. 16, 1934 2,102,008 Klitsche Dec, 14, 1937 2,362,873 Wessmann Nov. 14, 1944 FOREIGN PATENTS Number Country Date 3,881 Great Britain A. D. 1910 4,341 Great Britain Feb. 20, 1913 107.958 Germany Jan. 11, 1900 

